Magnetically separable and recyclable Fe3O4@PDA covalent grafted by l-cysteine core-shell nanoparticles toward efficient removal of Pb2+

Abstract Magnetic composites had attracted considerable attention owing to their outstanding properties in separation techniques. In this work, Fe3O4@polydopamine-g- l -cysteine (Fe3O4@PDA-g-L-Cys) core-shell composites were successfully fabricated via dopamine self-polymerization and zwitterionic cysteine covalent graft, aiming for removing Pb2+ from an aqueous solution. The structure and morphology of Fe3O4@PDA-g-L-Cys were verified by FT-IR, XRD, TEM and SEM. The factors (pH, adsorbent dosage, temperature, initial concentration, etc.) affecting the adsorption properties were systematically evaluated. Adsorption data were expressed by the Langmuir isotherm. The kinetic date of Fe3O4@PDA-g-L-Cysadsorbent for Pb2+adsorptionfitted the pseudo-second order kinetic model well. The obtained thermodynamics constantsΔG0, ΔH0, and ΔS0 indicated that process of Pb2+ removal by Fe3O4@PDA-g-L-Cys were endothermic and spontaneous.